An adapter for mounting equipment (4) such as lamps and headsets onto protective helmets includes a base (1) fastened detachably onto the protective helmet, and a holder (2) with variable securing parts (3) that snaps detachably into the base (1). The base (1) features a snap-and-detent mechanism (1.1), has an external shape adapted to the type of protective helmet and is fastened detachably onto the protective helmet. The holder (2) features a snap-and-detent element (2.5) designed as corresponding counter piece to the snap-and-detent mechanism (1.1) of the base (1). The variable securing parts (3) are flat silicone straps where at least two securing parts (3) can be threaded into the holder (2), an insertable piece of equipment (4) can be fastened separately, flexibly and detachably by wrapping the two securing parts (3) around the equipment (4) and anchoring them onto the holder (2), and the snap-and-detent element (2.5) of the equipped holder (2) snaps into the snap-and-detent mechanism (1.1) of the base (1) and, when in the base (1), is incrementally rotatable and detainable around the axis of the snap-and-detent element (2.5).